The present invention relates to polysiloxane based zwitterionic surfactants. Polysiloxane based surfactants have heretofore been either anionic, cationic, amphoteric or nonionic species. Such surfactants are useful as polyurethane foam additives, as mold release coatings, and in a variety of other applications. In general, polysiloxane based surfactants are more effective and efficient than their organic counterparts. For instance, polysiloxane based commercial surfactants reduce the surface tension of aqueous systems to about 20-25 dynes/centimeter whereas organic surfactants reduce the surface tension of such systems to about 30-35 dynes/centimeter. Furthermore, polysiloxane based surfactants achieve their optimal results with about one tenth to one one-hundredth the concentration with which organic surfactants achieve their optimal results.
Organic zwitterionic surfactants are known in the art to be compatible with a wide range of surfactants which allows them to be more readily formulated, and they are also known to be less irritating to eyes and skin than other types of surfactants. Thus, organic zwitterionic surfactants such as quaternized imidazoline derivatives are used in shampoos and soaps.
Zwitterionic organofunctional silicones are also known in the art, although to a much lesser extent than zwitterionic organic surfactants. DE 3,417,912 issued to Kollmeier, et al. and assigned to Th. Goldschmidt AG teaches betaine functional short polysiloxane chain materials of the general formula ##STR1## where M is a polysiloxane polymer; y is 2 to 4, z is 1 to 3, and R denotes an alkyl radical with 1 to 4 carbon atoms. UK patent application GB 2,161,172A, applied for by the Beecham Group, teaches the use of polysiloxane polyorganobetaine copolymers in shampoo formulations. Neither patent teaches the use of zwitterionic organofunctional polysiloxanes as a surfactant for lowering the surface tension of aqueous solutions. U.S. Pat. No. 4,496,705, issued to Florence et al. and assigned to the General Electric Corporation, teaches zwitterionic organofunctional polysiloxanes where the polysiloxane backbone of the finished product has a degree of polymerization of about 800. Florence teaches that these materials are elastomers which show improved adhesion to glass over state of the art elastomers. Florence et al. does not teach that these materials are surface active agents particularly effective in lowering the surface tension of aqueous solutions.
Graiver et al. teach organofunctional polysiloxanes of the general formula ##STR2## where M is a polysiloxane polymer. These materials are zwitterionic at certain pH values. See "Polysiloxane Zwitterionomers and Related Model Compounds", Parts I-III, Journal of Polymer Science, Polymer Chemistry Edition. V.17 p3559-3605 (1979). Graiver et al. do not teach that their materials, which differ from the claimed compositions of the present application in that they are not alkyl quaternary ammonium salts, are effective surface active agents which can lower the surface tension of aqueous solutions.